1. Field
An exemplary embodiment described technology relates generally to a laser irradiation apparatus. More particularly, the described technology relates generally to a laser irradiation apparatus that performs crystallization by irradiating a laser beam to a semiconductor layer.
2. Description of the Related Art
Most flat panel display devices, such as an organic light emitting diode (OLED) display, a liquid crystal display (LCD), and the like, include a thin film transistor. Particularly, a low temperature polycrystalline silicon thin film transistor (LTPS TFT) having good carrier mobility can be applicable to a high speed operational circuit and can be used for a CMOS circuit. As such, the LPTS TFT has been commonly used.
The LTPS TFT includes a polycrystalline silicon film that may be formed by crystallizing an amorphous silicon film. Methods for crystallizing the amorphous silicon film include a solid phase crystallization method, an excimer laser crystallization method, and a crystallization method using a metal catalyst.
Among various crystallization methods, crystallization methods using a laser beam have been widely used because it enables low temperature process so that a thermal effect on a substrate is relatively low and it enables making a polycrystalline silicon layer having a relatively excellent carrier mobility, e.g., as high as over 100 cm2/Vs.
However the crystallization method using laser may require scanning each semiconductor with slit-patterned laser beams. Thus, the crystallization method using laser has a problem in that the throughput per unit hour is significantly decreased compared to other crystallization methods.
The above information disclosed in this section is only for enhancement of understanding of the background of the described technology. Therefore, it may contain information that does not form prior art that is already known in this country to a person of ordinary skill in the art.